JP2005154098A - Fork leveling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically make a fork horizontal, with simplified structure, and reduce costs in a fork leveling device applied to a cargo handling vehicle. <P>SOLUTION: The fork leveling device comprises the fork 2, a tilt cylinder 3, a tilt control valve 4, a tilt lever 5, a horizontal condition detector 6, a forward tilting detector 7, a high lift height position detector 8, a horizontal stop valve 9, and a speed reducing valve 10. The horizontal condition detector 6 detects that the fork 2 is horizontal, and the forward tilting detector 7 detects that the tilt lever 5 is operated to be tilted forward. The high lift height position detector 8 detects that the fork 2 is in a high lift height position. The horizontal stop valve 9 is controlled by at least the forward tilting detector 7 and the horizontal condition detector 6, wherein the tilt lever 5 is operated to be tilted forward, and can stop forward tilting operation of the tilt cylinder 3 when the fork 2 gets horizontal. The speed reducing valve 10 is controlled by the high lift height position detector 8 and can reduce operation speed of the tilt cylinder 3 when the fork 2 is in the high lift height position. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an improvement in a fork leveling device that is applied to a cargo handling vehicle such as a forklift to automatically level the fork.

Conventionally, as this kind of fork leveling device, for example, the following is known.
(1) Using a variable period sounding means (buzzer or the like) to manually level the fork (Patent Document 1).
(2) A fork that is automatically leveled using various sensors and a controller (microcomputer) (Patent Documents 2 to 7).

Japanese Utility Model Publication No. 5-72899 Japanese Patent Laid-Open No. 7-61791 JP-A-8-119596 JP-A-9-156895 JP 10-273293 A Japanese Patent Laid-Open No. 11-171494 Japanese Patent Laid-Open No. 2003-63792

  However, although the former has a relatively simple structure, it still has to be operated manually because the fork must be leveled manually. Although the latter can automatically level the fork, there is a problem that the structure is complicated and the cost is high due to the use of expensive sensors and controllers.

  The present invention was devised in view of the problems described above, and the problem is that the fork can be automatically leveled, yet the structure is simple and the cost is excessive. It is to provide a fork leveling device that does not exist.

  The fork leveling device of the present invention basically includes a fork that can be raised and lowered, a tilt cylinder that tilts the fork, a tilt control valve that controls the operation of the tilt cylinder, and a tilt lever that operates the tilt control valve. And a horizontal detector that detects that the fork has become level, a forward tilt detector that detects that the tilt lever has been tilted forward, and an elevated position that detects that the fork has reached the elevated position. A horizontal stop valve that can be controlled by at least a forward tilt detector and a horizontal detector to tilt the tilt lever forward and stop the tilt cylinder from being tilted forward when the fork becomes horizontal; A speed reducing valve that is controlled by a high lift position detector and can reduce the operating speed of the tilt cylinder when the fork is in the high lift position. It resides features.

When the tilt lever is tilted forward, the tilt cylinder is tilted forward by the tilt control valve to tilt the fork forward. When the tilt lever is tilted backward, the tilt cylinder is tilted back by the tilt control valve to tilt the fork backward.
When the fork is changed from the backward tilted state to the horizontal state, the tilt lever is tilted forward. Then, this is detected by the forward tilt detector, and the tilt cylinder is tilted forward by the tilt control valve, so that the fork is returned from the rear tilt state to the horizontal state. When the fork is in a horizontal state, this is detected by the horizontal detector, and the horizontal stop valve is operated by the horizontal detector and the forward tilt detector to stop the forward tilting operation of the tilt cylinder. Put into a state.
When the fork is in the elevated position, the speed reducing valve is controlled by the elevated position detector to reduce the operating speed of the tilt cylinder. Therefore, in the process where the fork is in the elevated position and returned to the horizontal state from the backward tilted state and stopped, the operating speed is reduced, so that the shock when automatically stopping is reduced. Can do.
Since only the horizontal detector, the forward tilt detector, the elevated position detector, the horizontal stop valve, and the speed reduction valve are provided, the structure is relatively simple and the cost is not excessive.

  It is preferable that the fork is provided so as to be movable up and down on the tiltable mast, the tilt cylinder is provided so as to tilt the mast, and the horizontal detector is provided to detect the vertical position of the mast. . In this way, it can be easily applied to a counterbalance forklift.

  The horizontal stop valve is controlled by the forward tilt detector, the horizontal detector, and the elevation position detector, and when the fork is in the elevated position, the tilt lever is operated forward and the tilt is It is preferable that the forward tilting operation of the cylinder can be stopped. In this way, the fork can be automatically leveled only when the fork is in the elevated position.

According to the present invention, the following excellent effects can be achieved.
(1) Consists of fork, tilt cylinder, tilt control valve, tilt lever, horizontal detector, forward tilt detector, high lift position detector, horizontal stop valve, speed reducing valve, especially fork is horizontal A horizontal detector that detects the tilt lever, a forward tilt detector that detects that the tilt lever has been tilted forward, an elevated position detector that detects that the fork has reached the elevated position, and at least a forward tilt detector The tilt lever is controlled to be tilted forward by the horizontal detector and the tilt lever, and when the fork is leveled, it is controlled by the horizontal stop valve that can stop the tilt cylinder from tilting forward, and the lift position detector. The fork can be leveled automatically when the fork is in the uplift position, so that the fork can be leveled automatically and the structure is simple. It doesn't cost much.
(2) Since only a horizontal detector, a forward tilt detector, an elevated position detector, a horizontal stop valve, and a speed reduction valve are provided, it can be easily applied to existing ones.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a hydraulic circuit diagram showing a fork horizontal device of the present invention. FIG. 2 is an electric circuit diagram.

  The fork leveling device 1 includes a fork 2, a tilt cylinder 3, a tilt control valve 4, a tilt lever 5, a horizontal detector 6, a forward tilt detector 7, an elevation position detector 8, a horizontal stop valve 9, and a speed reduction valve 10. Therefore, the main part is constituted and applied to a cargo handling vehicle 50 such as a forklift.

  In this example, the cargo handling vehicle 50 is a counterbalance forklift, and is capable of traveling forward and backward to the vehicle body 51 that can travel, a counterweight (not shown) provided on the rear side thereof, and the front side of the vehicle body 51. The mast 52 provided, the fork 2 provided so as to be able to move up and down along the mast 52, the tilt cylinder 3 provided on the vehicle body 51 for tilting the mast 52 back and forth, and the lift provided on the mast 52 for raising and lowering the fork 2 A cylinder (not shown) is provided.

  The fork 2 can be moved up and down and tilted. In this example, the fork 2 has a substantially L shape, and is provided on a mast 52 that can tilt back and forth with respect to the vehicle body 51.

  The tilt cylinder 3 tilts the fork 2. In this example, the tilt cylinder 3 is interposed between the vehicle body 51 and the mast 52, and includes a forward tilt side working chamber (tail chamber) 11 and a rear tilt side working chamber (rod chamber). 12 is provided.

The tilt control valve 4 controls the operation of the tilt cylinder 3, and in this example, a six-port, three-position type manual switch having a forward tilt position (right position in FIG. 1), a neutral position, and a rear tilt position. The P port is connected to the discharge side of the pump 14 via the check valve 13, the P ′ port is connected to the discharge side of the pump 14, the T port and the P ″ port are connected to the tank 15, and the A port is the tilt cylinder 3. Are respectively connected to the forward-inclined working chamber (tail chamber) 11.
The pump 14 is driven to rotate by a prime mover 16 such as an engine or a motor. The suction side is connected to the tank 15, and a relief valve 17 is interposed between the discharge side and the tank 15. ing. An oil liquid is stored in the tank 15.

  The tilt lever 5 operates the tilt control valve 4. In this example, the tilt lever 5 is provided so as to tilt forward and backward on the fixed side in order to operate the spool of the tilt control valve 4.

  The horizontal detector 6 detects that the fork 2 has become horizontal. In this example, the horizontal detector 6 is a limit switch (LS1), and is provided on the vehicle body 51 side. The horizontal detector 6 is turned on when the mast 52 is in the vertical position. It is supposed to become.

  The forward tilt detector 7 detects that the tilt lever 5 has been tilted forward. In this example, it is a limit switch (LS2), and is provided on the fixed side in the vicinity of the tilt lever 5, The tilt lever 5 is turned on when it is tilted forward from the neutral position.

  The uplift position detector 8 detects that the fork 2 is in the uplift position. In this example, the uplift position detector 8 is a limit switch (LS3), and is provided on the mast 52. It is supposed to turn on when in position.

  The horizontal stop valve 9 is controlled by at least the forward tilt detector 7 and the horizontal detector 6 so that the tilt lever 5 is tilted forward, and when the fork 2 becomes horizontal, the tilt tilting operation of the tilt cylinder 3 is stopped. In this example, the tilt lever 5 is controlled to be tilted forward by being controlled by the forward tilt detector 7, the horizontal detector 6, and the elevated position detector 8 so that the fork 2 is in the elevated position. At the same time, when the fork 2 becomes horizontal, the tilting operation of the tilt cylinder 3 can be stopped, and a two-port two-position electromagnetic valve having a communication position and a check position is provided. The A port of the horizontal stop valve 9 is connected to the backward tilt side working chamber (rod chamber) 12 of the tilt cylinder 3.

  The speed reduction valve 10 is controlled by the high lift position detector 8 and can reduce the operating speed of the tilt cylinder 3 when the fork 2 is in the high lift position. In this example, the variable throttle valve 18 and A three-port two-position cut-off electromagnetic valve 19 connected in parallel is provided. The variable throttle valve 18 has one port connected to the B port of the tilt control valve 4 and the other port connected to the P port of the horizontal stop valve 9. The cutoff solenoid valve 19 has a P port connected to the B port of the tilt control valve 4, an A port connected to the P port of the horizontal stop valve 9, and a T port blinded.

  The horizontal stop valve 9 and the speed reduction valve 10 are integrated into a so-called unit as shown by a chain line in FIG.

  In FIG. 2, LS1 is a limit switch that is a horizontal detector 6, LS2 is a limit switch that is a forward tilt detector 7, LS3 is a limit switch that is a high-lift position detector 8, and SOL1 is a horizontal stop valve 9. Solenoid, SOL2 is solenoid of solenoid valve 19 constituting speed reduction valve 10, MS is main switch for selecting whether or not fork horizontal device 1 is functioned, R1, R2 and R3 are relays, D is a diode, respectively Show.

Next, the operation will be described based on such a configuration.
When the fork leveling device 1 is not functioned, the main switch MS is turned off as shown in FIG. 2 does not function at all, the horizontal stop valve 9 is maintained at the communication position (left side position in FIG. 1), and the on / off electromagnetic valve 19 of the speed reduction valve 10 is at the communication position (FIG. 2). 1 right side position).
In this state, when the tilt lever 5 is tilted forward as shown by the chain line in FIG. 1, the tilt control valve 4 is switched to the forward tilt position (right position in FIG. 1), and the pressure oil from the pump 14 is discharged. The check valve 13 → the tilt control valve 4 → the tilt cylinder 3 is supplied to the forward tilting side working chamber 11, and the oil in the tilting cylinder 3 backward tilting side working chamber 12 is turned off by the horizontal stop valve 9 → the speed reducing valve 10. The valve 19 is returned to the tilt control valve 4 → the tank 15. As a result, the tilt cylinder 3 is tilted forward (elongated) and the mast 52 is tilted forward, whereby the fork 2 is tilted forward.
On the contrary, when the tilt lever 5 is tilted backward, the tilt control valve 4 is switched to the rearward tilt position (left side position in FIG. 1), and the pressure oil from the pump 14 is checked valve 13 → tilt control valve 4 → The solenoid valve 19 of the speed reduction valve 10 → the horizontal stop valve 9 → the tilted cylinder 3 is supplied to the backward working chamber 12 and the oil in the forward working chamber 11 of the tilt cylinder 3 is supplied to the tilt control valve 4 → tank 15 Returned to As a result, the tilt cylinder 3 is tilted backward (shortened) and the mast 52 is tilted backward, whereby the fork 2 is tilted backward.

In order to automatically level the fork 2 that is tilted rearward and in the uplift position, that is, when the fork leveling device 1 is to function, the main switch MS shown in FIG. 2 is turned on and the tilt lever 5 is The forward tilt operation is performed as indicated by the chain line in FIG.
Then, the mast 52 is tilted forward by the tilt cylinder 3 and the fork 2 is tilted forward. At this time, since the fork 2 is in the uplift position, the limit switch LS3 which is the uplift position detector 8 is turned on, and the forward tilt detector 7 is activated by the tilt lever 5 being tilted forward. The limit switch LS2 is turned on. When the limit switch LS3 which is the elevation position detector 8 is turned on, the coils of the relays R1 and R3 are excited and the normally open contact is closed. When the normally open contact of the relay R1 is closed, the solenoid SOL2 is excited to switch the open / close solenoid valve 19 to the shut-off position, and the variable throttle valve 18 functions as the speed reduction valve 10. For this reason, the oil returned to the tank 15 from the backward tilt side working chamber 12 of the tilt cylinder 3 is throttled by the variable throttle valve 18 of the speed reduction valve 10, and the backward tilt operation of the tilt cylinder 3 is decelerated. When the mast 52 is in the vertical position and the fork 2 is in the horizontal state, the limit switch LS1 that is the horizontal detector 6 is turned on. When the limit switch LS1 that is the horizontal detector 6 is turned on, the limit switch LS2 that is the forward tilt detector 7 is turned on first, so that the coil of the relay R2 is excited and its normally open contact is Closed. When the normally open contact of the relay R2 is closed, since the normally open contact of the relay R3 is closed first, the solenoid SOL1 is excited and the horizontal stop valve 9 is switched to the check position. For this reason, the oil recirculated from the tilting side working chamber 12 to the tank 15 from the tilt cylinder 3 is blocked by the horizontal stop valve 9 and the mast 52 is stopped in the vertical position so that the fork 2 is brought into a horizontal state. Stopped. Thereafter, when the tilt lever 5 is returned to the neutral position, the tilt cylinder 3 is held in the above-described state, and the fork 2 is maintained in a horizontal state. If the tilt lever 5 is tilted backward from such a state, the mast 52 and the fork 2 are tilted backward.

When the fork 2 is in the uplift position, this is detected by the uplift position detector 8 and the variable throttle valve 18 of the speed reduction valve 10 is operated. Tilt motion is decelerated. In particular, in the process in which the fork 2 is in the high lift position and returned to the horizontal state from the rearward tilting state and stopped, the operating speed is reduced, so that the shock when automatically stopping is reduced. I can do things.
Since only the horizontal detector 6, the forward tilt detector 7, the elevation position detector 8, the horizontal stop valve 9 and the speed reduction valve 10 are added, the structure is relatively simple and the cost is not excessive.

In the above example, the fork leveling device 1 is applied to a counterbalance type forklift. However, the fork leveling device 1 is not limited thereto, and may be applied to a reach type forklift.
In the previous example, the horizontal detector 6 detects the vertical position of the mast 52. However, the horizontal detector 6 is not limited to this. For example, the horizontal detector 6 may directly detect the horizontal position of the fork 2.
In the previous example, the horizontal detector 6, the forward tilt detector 7, and the elevation position detector 8 used limit switches. However, the present invention is not limited thereto, and for example, proximity switches or the like may be used.
In the previous example, the horizontal stop valve 9 is a two-port two-position solenoid valve having a communication position and a check position. However, the horizontal stop valve 9 is not limited to this, and for example, a cut-off two-port two-position solenoid valve is used. May be.
In the above example, the horizontal stop valve 9 and the speed reduction valve 10 are provided in the pipeline between the tilting working chamber 12 of the tilt cylinder 3 and the tilt control valve 4. May be provided in a pipe line between the forward tilting working chamber 11 and the tilt control valve 4.
In the previous example, the speed reduction valve 10 is a three-port two-position solenoid valve.

The hydraulic circuit diagram which shows the fork horizontal apparatus of this invention. Electrical circuit diagram.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fork leveling device, 2 ... Fork, 3 ... Tilt cylinder, 4 ... Tilt control valve, 5 ... Tilt lever, 6 ... Horizontal detector, 7 ... Forward tilt detector, 8 ... High lift height detector, 9 ... Horizontal Stop valve, 10 ... Speed reducing valve, 11 ... Forward tilt side working chamber, 12 ... Back tilt side working chamber, 13 ... Check valve, 14 ... Pump, 15 ... Tank, 16 ... Priming motor, 17 ... Relief valve, 18 ... Variable throttle Valve 19, cut-off solenoid valve 50, cargo handling vehicle 51, vehicle body 52, mast LS 1 limit switch (horizontal detector) LS 2 limit switch (forward tilt detector) LS 3 limit switch (lifting height) Position detector), SOL1 ... solenoid of horizontal stop valve, SOL2 ... solenoid of solenoid valve constituting speed reduction valve, MS ... main switch, R1, R2, R3 ... relay, D ... diode.

Claims (3)

  A liftable and tiltable fork, a tilt cylinder that tilts the fork, a tilt control valve that controls the operation of the tilt cylinder, a tilt lever that operates the tilt control valve, and a horizontal that detects when the fork is leveled A detector, a forward tilt detector that detects that the tilt lever has been tilted forward, an elevated position detector that detects that the fork has reached the elevated position, and at least a forward tilt detector and a horizontal detector. The tilt lever is operated to tilt forward and the fork is leveled, and when the fork is leveled, the tilt cylinder is stopped and the fork is lifted by the vertical stop position detector. A fork leveling device characterized by comprising a speed reducing valve capable of reducing the operating speed of the tilt cylinder when in a high position.   The fork is provided so as to be movable up and down on a tiltable mast, the tilt cylinder is provided so as to tilt the mast, and the horizontal detector is provided for detecting a vertical position of the mast. Fork leveling device as described in. The horizontal stop valve is controlled by the forward tilt detector, the horizontal detector, and the elevation position detector, and when the fork is in the elevated position, the tilt lever is operated forward and the tilt is The fork leveling device according to claim 1, wherein the forward tilting operation of the cylinder can be stopped.

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